Means for controlling the speed of a charging plunger in a die casting machine



Feb. 13, 1962 SELI'US 3,020,607

G. NY MEANS FOR CONTROLLING THE SPEED OF A CHARGING PLUNGER IN A DIECASTING MACHINE Filed June 25, 1959 46 T l f INVENTOR Gz srm A ysn/usATTORNEY United States Patent 3,020,607 MEANS FOR CONTROLLING THE SPEED'OF A CHARGING PLUNGER IN A DIE 1 CASTING MACHINE Gustav Nyselius,Newficld Ave., Stamford, Conn. Filed June 25, 1959, Ser. No. 822,848 4Claims. (CI. 2268) This invention relates to die casting machines of thekind employing a reciprocating plunger to move a charge into a diecavity, and more particularly to means for varying the speed of travelof the plunger.

Heretofore in apparatus of the kind described the die charging plungerhas either been moved at a single uniform speed, or first at one speedand then at a second faster speed, each phase of the charging strokebeing at a substantially uniform speed.

It is an object of this invention to provide improved means for varyingthe speed of travel of the charging plunger.

Another object of the invention is to provide a device in which thespeed of the plunger may be continuously varied through all or a portionof its charging stroke.

Another object of the invention is to provide an apparatus which issimple, practical and dependable.

The invention will best be understood if the following description isread in connection with the drawings in which FIGURE 1 is a sideelevation partly in cross section and FIGURE 2 is a vertical sectionalview taken on the line 2--2 of FIGURE 1. v

The apparatus comprises the vertical frame members and 12 interconnectedby the tie rods 14. Mounted in and extending between from members 10 and12 is a cylinder 16. Member 10 has the bore 11 the wider portion 11a ofwhich receives the forward end of cylinder 16 and the narrower portion11b of which provides a passage for the plunger 18 the piston portion18a of which is reciprocable within cylinder 16. Member 12 has a bore 13the wider portion 13a of which receives the rear end of cylinder 16 andthe narrower portion 13b of which is a port through which fluid underpressure is introduced into the rear end of cylinder 16 and into contactwith the rear end of plunger 18. The end of fluid port 13b which isremote from plunger 18 is enlarged and forms a coupling c for a fluidconduit 20' extending from a reservoir (not shown) of fluid underpressure through a 4-way valve 22 the position of which determineswhether fluid under pressure is supplied into, or exhausted from therear end of cylinder 16 through port 13b.

Within frame member 12 is a vertical slideway 24 for a slide or gatevalve member 26 the lower end of which extends into port 13b andcontrols it, and the upper end of which supports the roller 28 which isa cam follower adapted to travel on the cam surface 30 of the slidingcam member 32. It will be noted that a small passage 27 is providedextending through valve member 26 adjacent its lower end and is open atall times.

Member 32 extends through a horizontal slideway 34 provided in the upperend of frame member 12 and defined on top by the rollers 36. When 4-wayvalve 22 is turned to supply fluid under pressure into the rear end ofcylinder 16 through port 13b the force of said fluid, acting first onlywithin passage 27 in member 26, starts raising member 26 in its slideway24, and as the lower end of member 26 is uncovered by moving away fromthe lower surface of port 13b the force of the fluid acting now on theentire lower end of slide valve 26 continues to raise member 26 untilits cam follower roller 28 contacts and is held against the cam surface30 of sliding cam 32.

It will be noted that at least a portion of the cam surface 30 isinclined providing a surface of varying elel-z vation relative to port13b. This surface of varying, ele--- vation controls the height to whichmember 26 can riseand in so doing vary the sizeof the opening throughwhich fluid under pressure is introduced into the re ar end of cylinder16 into contact with the rear. end of the piston portion 18a of plunger18. I In the drawing only the rear end portion of a die char g ingplunger is fully shown but the front end of the portion which isillustrated is provided with a bayonet slot 38- for ready attachment toa suitable front section 19.

Attached to and moving with the plunger 18 is the vertical bracket 40. Aslide cam extension 42 is ad-. justably attached to the front end of cammember 32 and the forward end of said extension is supported in a bear-,ing 44 provided in the upper portion of frame member 10 and extendsthrough the bore 46 in the upper end of bracket 40 to which it isdetachably secured as by the nut 48.

It will be seen that when 4-way valve 22 is turned to supply fluid underpressure tothe rear end of plunger 18 a small amount of said fluid willflow through passage 27 in slide valve 26 and will cause the plunger 18to start forward slowly and will urge slide valve 26 to rise to theextent permitted by the cam surface 30. Since bracket 40 and cam member32 will move forward with the plunger the cam surface 30 will move overthe cam follower roller 28 on the top of valve member 26 and the latterwill start to rise as soon as it starts riding on the upwardly inclinedportion x of the cam surface. As valve member 26 moves upwardprogressively the port 13b is correspondingly opened admitting more highpressure fluid into the rear end of cylinder 16 and progressivelyincreasing the speed of the plunger in moving through its chargingstroke. The speed of the plunger is varied in direct relation to theslope of cam surface 30.

The plunger 18 is returned in a known manner by turning 4-way valve 22to exhaust the pressure fluid from the rear end of cylinder 16 and tointroduce it into the front end of cylinder 16 through conduit 50leading from the 4-way valve 22. As plunger 18 is returned to itsstarting position slide valve member 26 will fall as the fluid pressurein the rear end of cylinder 16 and port 13b is reduced and the slope ofcam surface 30 forces it to return to its starting position.

There has thus been provided thoroughly practical means for varying thespeed of travel of the charging plunger of a die casting machine.

What I claim is:

1. In apparatus of the kind described including a reciprocable plungerhaving a piston portion enclosed in a cylinder and means for introducingfluid under pressure alternately into opposite ends of said cylinder toreciprocate the plunger, a port through which said fluid is supplied to,and exhausted from, the rear end of said cylinder, a gate valveextending into said port reciprocable in a plane normal to the axis ofsaid port, and cam means moveable in response to movement of the plungerand having a cam surface disposed to limit opening move ment of saidgate valve.

2. In a die casting machine of the kind employing a reciprocable plungerto move a charge into a die cavity, the plunger including a pistonportion enclosed in a cylinder, means including an entrance port forsupplying fluid under pressure into said cylinder while exhausting fluidfrom the other end of the cylinder to move the plunger through itscharging stroke, a cam moveable with the plunger, a gate valve disposedin said port, and extending into contact with the surface of said cammember, said gate valve having a surface portion exposed at all times tofluid pressure in said port and acting to direct a com-Patented-Feb.'13, 196a ponent of said pressure in a direction tending tolift the gate valve against said earn.

3. An apparatus of the kind described including a reciprocable plungerhaving a piston portion enclosed in a cylinder and means for introducingfluid under pressure alternately into opposite ends of said cylinder toreciprocate the plunger, a port through which said fluid is supplied toan exhaust from the rear end of said cylinder, a cam with an inclinedsurface moving with the plunger, and a gate valve between the port andthe cam and having a fluid channel extending transversely to the axis ofthe valve, whereby said valve is responsive to pressure in the port tomove in an opening direction to the extent permitted by the cam surface.

4. In a die casting machine of the kind employing a reciprocal plungerto move a charge into a die cavity, a frame and a plunger reciprocablein said frame, said plunger having an enlarged rear-end portion, acylinder enclosing said enlarged rear-end portion, and means forinclined surface portion sloping away from the axis of reciprocating theplunger by means of fiuid under pres- 2 the plunger, said gate valvebeing moveable in the direction of the cam and having a small passageextending axially of the port and of sufiicient size to initiatemovement of the valve member in response to fluid pressure 7 in theconduit means leading to said port when such movement is permitted bythe slope of said cam.

Bishop et al Apr. 25, 1933 Hodler Dec. 18, 1956

